MPGs run, Aspire SE

[zoom zoom]

If its a pic you just need loaded temporarily (good for 3+ years but does eventually disappear) you could use tinypic.com


I was suggesting 175's because you said you did the mpg run on 185's. 165's are hard for me to find, i'd personally like a new set of 175/50/13's but I don't think it will ever happen.

[mikeyjd]

Interesting. Earlier today I was wondering what racecars did. Driving on smooth tracks, they have very low air dams. Do they also have belly pans or is that even necessary? Because of their much higher speeds, I could imagine that there would be more advantage for them to have both, since higher speeds would mean higher pressure for what little air did get under the dam.

Today I built better dams for both the Aspire and my Festy. They wrap all the way around under the bumper. I will test the Festy one tmw probably. The Aspire one I will test next week, after I get side skirts on.

Racecars have them because they also add down force. Anything lower than the lowest hanging underside part will just be adding the frontal area+down force without lowering CD.

[TominMO]

Thanks Dan and zoomx2.

[TominMO]

Here are three pics of the adapters and wheels I will be using. Today I will take pics of the tire and the two front dams.

[TominMO]

More pics:
Pic 1 is the Festy with air dam.
Pic 2 is the two tires in pic 3.
Pic 3 shows the 165/80x15, 155/80x12, and the newly-painted Accord space-saver rim. (Shouldn't have used a white background, it washed out the tire contrast.)
Pic 4 is the Aspire air dam.
For the air dams, I used body-colored duct tape. They will be painted the same color for durability; but some paint will inevitably come off, so I wanted the underlying duct tape to be the same color.

[Pu241]

Tom, thought I was almost going see if you wanted to go on a real test from STL to Bridgeport, OH.
Approx 550 miles one way, as a test, but looks like I got another plan working!
really looking forward to how this works out.
Might have some ABS sheet that can be used as slide skirts.
Maybe have a sheet of ABS for an under belly pan.
Tougher than Coroplas but harder to work with.

[TominMO]

OK, did a MPG run with the Festy.

Some relevant facts about this particular car, re drag/fuel consumption:
For:
air dam (I had a very small air dam on before, but this one is much larger)
Festiva roof spoiler
bumper openings and most grill openings blocked off
Against:
B6 motor
185/60x14 tires
wipers, two mirrors
no attempts made to lighten the car

Did the same 99.1-mile run on the hwy as I recently did in the Aspire. On two previous MPG runs, this car with the same tires, small dam, all other factors the same, got 41.9 MPG each time. Today I used 2.2 gallons over 99.1 miles, which came to 45.0 MPG. This is a 7% improvement. I was disappointed about this, but then realized that the previous small dam might have contributed to previous MPG runs, and this larger dam just improved the aero qualities a bit more.

As a side benefit, it was very quiet in there @ 60 MPH, which is 2400 RPM in 5th BTW.

Since I had a small air dam on there before, I say that the real test is to compare no air dam at all to this one. In that case I would expect maybe as much as a 10% difference. In which case my $10 mod will pay for itself (@ $3.50/gal) in about 30 gallons of gas. Even if I am wrong, it will pay for itself in about 45 gallons, then it's all savings after that.

Below is a summary of my MPG runs with this Festy. Today's is in bold. None of my tests involve hypermiling techniques BTW.
Speed....MPG
60.........41.9 (B6 motor, 185/60x14 tires, small front air dam)
60........45.0 (same as above + large front air dam)
60.........52.1 (B3 motor, 155/80x13 tires)
55.........58.5 (same as above)
45.........62.5 (same as above)
So you can see that two big variables besides aero are the motor and the tires. A 10% improvement via the air dam @ 60 MPH with the B3/skinny tires would give about 57.3 MPG. At 55 MPH you could expect perhaps 64.3 MPG.

[TominMO]

Largest MPG factors:
Adjusting the nut behind the wheel
motor size
transmission gearing (and tire height)
aero factors
car in good running condition (tune-up, wheel bearings, etc.)
weight (perhaps least important)

John, I think the Aspire could make the 550-mile trip to Bridgeport on one tank of gas, once I install side skirts and the taller tires.

[mikeyjd]

Largest MPG factors:
Adjusting the nut behind the wheel
motor size
transmission gearing (and tire height)
aero factors
car in good running condition (tune-up, wheel bearings, etc.)
weight (perhaps least important)

John, I think the Aspire could make the 550-mile trip to Bridgeport on one tank of gas, once I install side skirts and the taller tires.

I think aero factors are about as important as motor and gearing. You could probably get a b6 up ti 60mpg with enough aero work. Weight makes some difference in city driving or with pulse and glide but hardly any with steady state.

[TominMO]

1. I think aero factors are about as important as motor and gearing.
2. You could probably get a b6 up to 60mpg with enough aero work.
3. Weight makes some difference in city driving or with pulse and glide but hardly any with steady state.

1. Agreed.
2. I doubt you could in a Festy without a major body change like a boat-tail, but maybe you could in an Aspire due to better-designed aerodynamics. Skinny tires would help too; I have 185s on both cars.
3. Yeah, that makes sense.

[zoom zoom]

wow I wasn't expecting that kind of mpg's with a b6...me with my foot in the flooreverywhere I go, jacked up with no aero mods should net at least 36-38??

[TominMO]

wow I wasn't expecting that kind of mpg's with a b6...me with my foot in the flooreverywhere I go, jacked up with no aero mods should net at least 36-38??

Maybe so; why not do your own tests and report back to us?

Today I got one of the tall skinny 15" tires mounted and balanced, on the repainted rim, and the space-saver tire taken off the non-painted rim. Went home, mounted the new tire, and painted the other rim. Tmw I will have the other 15"er mounted, and get some temporary side skirts on. Then take it for an MPG run over the weekend, probably Sunday morning.

I noted that the tall tire with the adaptor does rub on the fender when turning. This adaptor is 1 1/4" thick, but I needed one to change the bolt pattern for the Aspire. I could have gone with 1" thick, but was concerned that the lug nuts holding it to the hub might protrude slightly, affecting mounting the rim. Oh well. Going to Lowe's now to get a thick 48" dowel (cheaper than a baseball bat) to "adjust" my fenders....If you were to go with this tire/wheel setup for a stock Festy 4x114.3 hub, I would recommend using long lug studs and two 6mm spacers per side. That should center it nicely between the spring and the fender, and be much cheaper than adaptors like I have.

Another thought: you could also get almost all of the height by going with a 185/75x14 tire, like the excellent and long-wearing Kumho Solus KR21, which is 25.0" tall. With a 14" rim with good backspacing, there would be no need for spacers or long studs. That does add a lot of rotating mass, so I think it would be more suitable for the Capri brake swap than stock Festy brakes.

[mikeyjd]

Maybe so; why not do your own tests and report back to us?

Today I got one of the tall skinny 15" tires mounted and balanced, on the repainted rim, and the space-saver tire taken off the non-painted rim. Went home, mounted the new tire, and painted the other rim. Tmw I will have the other 15"er mounted, and get some temporary side skirts on. Then take it for an MPG run over the weekend, probably Sunday morning.

I noted that the tall tire with the adaptor does rub on the fender when turning. This adaptor is 1 1/4" thick, but I needed one to change the bolt pattern for the Aspire. I could have gone with 1" thick, but was concerned that the lug nuts holding it to the hub might protrude slightly, affecting mounting the rim. Oh well. Going to Lowe's now to get a thick 48" dowel (cheaper than a baseball bat) to "adjust" my fenders....If you were to go with this tire/wheel setup for a stock Festy 4x114.3 hub, I would recommend using long lug studs and two 6mm spacers per side. That should center it nicely between the spring and the fender, and be much cheaper than adaptors like I have.

Another thought: you could also get almost all of the height by going with a 185/75x14 tire, like the excellent and long-wearing Kumho Solus KR21, which is 25.0" tall. With a 14" rim with good backspacing, there would be no need for spacers or long studs. That does add a lot of rotating mass, so I think it would be more suitable for the Capri brake swap than stock Festy brakes.

Awesome info Tom! I am trying to figure out the 100% best option for my current tire/wheel situation. I am taking my time as I got some brand new 185/65/12's given to me last month and I want to get at least a little use out of them even if they are only 22" total, and it will take me quite a while to pay off new 14's or 15's since I'm already at 60mpg with the 12's.

Edit: my car has a nice auto festy vacuum booster for the breaks and new calipers and pads as well so my breaks are top notch, and wouldn't want to invest in a new setup. It sounds like an adapter is my best bet, but I would want to avoid protrusions that would be counter productive. Thoughts?

[TominMO]

Awesome info Tom! I am trying to figure out the 100% best option for my current tire/wheel situation. I am taking my time as I got some brand new 185/65/12's given to me last month and I want to get at least a little use out of them even if they are only 22" total, and it will take me quite a while to pay off new 14's or 15's since I'm already at 60mpg with the 12's.

Edit: my car has a nice auto festy vacuum booster for the breaks and new calipers and pads as well so my breaks are top notch, and wouldn't want to invest in a new setup. It sounds like an adapter is my best bet, but I would want to avoid protrusions that would be counter productive. Thoughts?

OK, so you still have Festy brakes if you have 12s on. I'd put those 185/65x12s on the rear and look for larger front tires, like even 155/80x13s, which are 22.7" tall vs. 21.5" for the 185/65x12s.

But frankly I'd call the sweet spot about 24", which is a good 10% taller than stock 12s, very available, and can be used on "normal" rims. The Kumho Solus KR21 comes in 185/75x14. It is an excellent, long-wearing all-around tire, and at 24.2", you will have little or no front fender clearance issues, since the wheel/tire won't be sticking out from using a large spacer. Worst case, you might have to roll the front fenders a little. I think that the higher gearing it provides will more than offset the extra drag of a wider tire (compared to a 155).

Check out this selection at tires-easy: http://www2.tires-easy.com/cgi-bin/r...hen=View+tires
The Hankook is also good and quite cheap. I might stick these on my Capri 14" rims for the Festy.

[TominMO]

Here is my Aspire, completely modded for its test, shown on the grounds of the IAAAS (Institute for Advanced Automotive Aerodynamic Studies).

Mission Statement of the IAAAS: to create vehicles of such high MPG ratings that you will want to slap yo' momma.

Notes:
Front tires are 185/80x15 on 1992 Accord space-saver rims.
Rear tires are just some 155/80x13 snows I had laying around on Aspire steelies.
Side skirts are temporary and mainly held on with 90-MPH tape. Since I will only be going 60, this should be fine.
Had to remove front mudflaps due to rubbage.